Twin-Jet by Multiplex

20 Apr 14 - The Twin-Jet ready to fly yet again.

Twin-Jet - port front quarter Twin-Jet - Port Wing Tip Twin-Jet - Front Twin-Jet - Underside Twin-Jet - port front quarter Twin-Jet - front Twin-Jet - side Twin-Jet - underside

N° of launches / Time 6 0 hour 33 mins Not all flights logged
Wingspan 35.8 in 0.910 m  
Wing Area 395 in² 25.5 dm²  

Original Configuration New Configuration
Flying Weight 2 lb. 14½ oz 1315 g 2 lb. 13 oz. 1275 g
Wing Loading 16.9 oz/ft² 51.6 g/dm² 16.4 oz/ft² 50 g/dm²
Wing Cube Loading

10.2 - Just above the Aerobatic group

9.9 - 'Aerobatic'

Motor 2 x Graupner  480 BB Race 7.2V, wired in series 2 x Turnigy 480S BL In-runner brushless with fan 1500kv
Propeller 2 x Graupner Super 6" x 4" (Grey) reduced to 5" diameter 2 x APC-E 6" x 5"

12 Panasonic 4/5 Sub-C NiMH

Turnigy Nano-Tech 4S 2700mAh 65C+ or 3300mAh 35C+ LiPo
Speed Controller Schulze slim-25be - 6 to 12 cells - 25A continuous - BEC & Brake 2 x Turnigy Plush 40 brushless - 40A (55A burst) - 2-6S LiPo - 3A BEC - Brake
Receiver Webra Nano S6 - 6ch - PPM - 35 MHz OrangeRx R710 - 7ch - 2.4GHz (Spektrum DSM2 Compatible) - Internal and remote receiver
Servos Elevons - 2 x Hitec HS-81MG Elevons - 2 x Hitec HS-81MG
Static motor parameters  17000 RPM @ 20.0A, 12.7V, giving 254W and estimated 88W/lb. 16900 RPM @ 17.5A per motor (33A total), 13.65 V, giving 450W total and estimated 160 W/lb.
Flight performance Flies quite fast and climb is good, but I still need to do some experimenting with propellers. Will maintain a vertical climb and fast in level flight.  I reckon that the timer will be set at 8 minutes which is pretty good.

20 Apr 14 - I missed judged the height of the ground about a month ago; the Twin-Jet hit very hard, snapping 1 wing off and damaging both motor nacelles.  During that flight I measured a maximum speed of 96.2 mph (155 kph), which is pretty good.  Fortunately it's EPP and Gorilla Glue works wonders; it's ready to fly again with almost no weight change.

11 Jan 14 - I flew the Twin-Jet in it's new configuration and livery this afternoon.  It is pretty fast but might be better with Graupner Speed 6" x 6" propellers; something to try

3 Jan 14 - The friend I sold the Twin-Jet to initially seemed keen to fly it but never did; I eventually bought it back again as it seemed a shame.  In getting it going again I've gutted out all the equipment and refilled it with brushless in-runners, a LiPo pack and 2.4 GHz radio; resulting in a slighter lighter model with nearly twice the power.  It also now sports a new paint scheme, which is loosely based on a scheme used on some Russian MIG-31; the main difference being the underside of the wing is all white to aid orientation.  I may fit some stickers at some point but I quite like the minimalistic look.

17 Aug 07 - Sold to a friend.

21 Jun 01 - I bought this model at the Sandown Model Show on 2 Jun 01 along with the Multiplex Cargo, and I completed this model yesterday. Construction is the durable Elapor foam (EPP) as per the Pico-Jet Combat. The model is supplied with 2 Multiplex Permax 400 6v motors and standard Günther propellers. I want to upgrade the performance without significantly increasing the weight so 480 motors were to be used. I couldn't get standard 480s so took a pair of Graupner 480 BB Race 7.2v motors instead. These motors turned out to be a far hotter wind than I thought and I couldn't run them in parallel on 8 cells. I therefore decided to increase to 12 smaller cells with the motors in series. The Panasonic 2000 NiMH 4/5 Sub-C cells are considered good up to 30A and a 10 cell pack is almost identical in size to an 8 cell Sub-C pack. To make it different in appearance I have painted the aircraft white, with black panels for the cockpit glazing.

The first launch attempt ended abruptly when my hand when through the right hand propeller on the follow through. This broke the propeller in two and dislodged the motor. The out of balance propeller pulled the motor loose and the model cartwheeled into the ground. The only damage sustained to the model was a slightly crushed nose, the broken propeller and both motors knocked loose. I ended up with a nasty gash in my left index finger which will take much longer to heal than the model will to repair.

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